Most forge furnaces have a flue gas velocity of 50 feet per second with a maximum air pressure of 8 inches water column. By operating at such low pressures and velocities, the heat treat time for a given work piece is severely extended thereby increasing fuel consumption drastically.
In walking beam, rotary hearth, barrel type conveyorized endo feed, billet, annealing, and normalizing furnaces, the burners rely primarily on radiant heating and only secondarily upon forced convection. Since the rate of heat transfer by radiation is fixed, the heat transfer per time is also limited in such prior art furnaces.
The prior art burners are extremely complex and have multiple parts. Also, a large pressure drop occurs between the air blower and burner nozzle. Such a pressure drop is necessary in prior art burners to permit adequate control. The nozzle mix burners of the prior art are not able to achieve the small combustion chamber space and air/gas atom mixture of pre-mix systems.
Eclipse and North American both manufacture a relatively high velocity burner. Their burners operate at a back pressure of approximately 8 inches water column in the combustion chamber. Although such burners can operate at a velocity of 500 feet per second, their design is not conducive to mounting multiple burners in a common manifold combustion block or to controlling multiple burners with one control system. Such burners require individual controls for each burner and each burner is required to have its own air manifold, ignition system, and flame scanner. Such systems require an excessive size of combustion chamber thereby requiring additional heat.
High velocity burners which have a low fire position operate in an excess air mode which may or may not be suitable for a particular customer. Such systems have an auxiliary air source not regulated by the air/gas mixtures whereby as the air/gas mixture is turned down, such burners become oxidizing or an excess air burner.
The invention overcomes these defects in the prior art combustion systems and burners.